.\"	$Header$
.\"
.\" Copyright (c) 1991-1997 Sam Leffler
.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
.\"
.\" Permission to use, copy, modify, distribute, and sell this software and 
.\" its documentation for any purpose is hereby granted without fee, provided
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.\"
.if n .po 0
.TH RGB2YCBCR 1 "November 2, 2005" "libtiff"
.SH NAME
rgb2ycbcr \- convert non-YCbCr
.SM TIFF
images to a YCbCr
.SM TIFF
image
.SH SYNOPSIS
.B rgb2ycbcr
[
.I options
]
.I "src1.tif src2.tif ... dst.tif"
.SH DESCRIPTION
.I rgb2ycbcr
converts
.SM RGB
color, greyscale, or bi-level
.SM TIFF
images to YCbCr images by transforming and sampling pixel data. If multiple
files are specified on the command line each source file is converted to a
separate directory in the destination file.
.PP
By default, chrominance samples are created by sampling
2 by 2 blocks of luminance values; this can be changed with the
.B \-h
and
.B \-v
options.
Output data are compressed with the
.SM PackBits
compression scheme, by default; an alternate scheme can be selected with the
.B \-c
option.
By default, output data are compressed in strips with
the number of rows in each strip selected so that the
size of a strip is never more than 8 kilobytes;
the
.B \-r
option can be used to explicitly set the number of
rows per strip.
.SH OPTIONS
.TP
.B \-c
Specify a compression scheme to use when writing image data:
.B "\-c none"
for no compression,
.B "\-c packbits"
for the PackBits compression algorithm (the default),
.B "\-c jpeg"
for the JPEG compression algorithm,
.B "\-c zip"
for the deflate compression algorithm,
and
.B "\-c lzw"
for Lempel-Ziv & Welch.
.TP
.B \-h
Set the horizontal sampling dimension to one of: 1, 2 (default), or 4.
.TP
.B \-r
Write data with a specified number of rows per strip;
by default the number of rows/strip is selected so that each strip
is approximately 8 kilobytes.
.TP
.B \-v
Set the vertical sampling dimension to one of: 1, 2 (default), or 4.
.SH "SEE ALSO"
.BR tiffinfo (1),
.BR tiffcp (1),
.BR libtiff (3)
.PP
Libtiff library home page:
.BR http://www.simplesystems.org/libtiff
